


acu traiectatur duo lina ducente (thread the needle with two threads)

by orbitalknight



Category: Kamen Rider Build
Genre: Alternate Universe - Fantasy, Canon Retelling and then Canon Divergence, M/M, Other Additional Tags to Be Added, Slow Burn
Language: English
Status: In-Progress
Published: 2019-01-28
Updated: 2019-02-03
Packaged: 2019-10-18 11:20:52
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,800
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17579885
Author URL: https://archiveofourown.org/users/orbitalknight/pseuds/orbitalknight
Summary: Sento Kiryuu, brilliant spellcaster and curse-breaker, lives on the charity of a tavern owner and in the company of a black and white rabbit.Ryuuga Banjou is a disgraced knight on the run with hands that sometimes crackle with a bright blue flame.Fate, it seems, insists upon their meeting.





	1. abiit excessit evasit erupit

There was only the blood pounding in his ears and breath coming in gasps as ragged as the clothes he wore. 

The fabric stank of the gallows, of prison, of everything Ryuuga Banjou was trying to outrun, crushing twigs and foliage under his bare feet. Even while the stench clouded his lungs it spurred him forward, through the trees and the underbrush, deeper and deeper into the woods that ringed the Proelio Castle town. He didn’t have time to think about how he’d escaped, the way the noose had snapped at the critical moment and left the audience of the hanging suspended in surprise even as he fell through the gallows platform. He’d tumbled through the trapdoor and scrambled like a desperate lizard out from underneath the rotting wooden beams that had hosted so many deaths already. For the first time he could remember, Banjou had been grateful for those laps he’d run around the jousting course on the castle grounds with the other knights.

He let the past catch up to him, just for that moment, one hand braced against a tree. He didn’t hear anyone following him, or being obvious about it if they were. The hand against the tree curled into a fist, slammed into the bark. It stung, but no more than everything else. 

“What the hell?” Banjou spat the words into the grass.

He lowered himself to a squatting position the ground, something bitter on the tip of his tongue, in the back of his throat. This wasn’t how it was supposed to go. He was going to do his time, undeserved as it was, and then get back on his feet however he had to. It was a tip picked up from tavern brawling, good advice for the unsavory nature of the way he’d come by it. Higher bets if you got back up again and again. It was advice like that which stuck to his ribcage, even when it was bruised from a night of good money, far more than any code of chivalry he’d sworn to engrave upon his heart. Not that he really wanted to go back to brawling, but before the hanging had been announced, Banjou had every intention of collecting on those wagers. 

Something in the underbrush rustled, and Banjou startled to attention, tensing into a sprinting position. It was not a pursuer or authority of any kind lurking there,  but a black and white rabbit that came snuffling out of the bushes. The rabbit had bright eyes and a pinkish nose that wiggled in Banjou’s direction as it leaned back onto its haunches. It was a cute little thing, undeniably, floppy-earned with a glossy coat and bit of roundness to it. Banjou wondered how it wasn’t boiling away in someone’s soup pot already, looking like that. Still, he didn’t have the time to be sitting around moping for the amusement of fuzzy woodland creatures. He stood up again, the muscles in his legs crying out in protest, figuring that the sudden movement would be enough to scare the rabbit back to where it had hopped out from. Instead, the rabbit leaned back further, beady eyes still locked on Banjou. He was locked in place by the stare, the strangely human nature of it. 

Banjou was still staring when something much larger came through the shrubbery, with such care and speed that could only be ascribed to a deep familiarity with the woods. There was a jingling of glass on glass, and two mismatched boots, a pair of trousers torn just below the knees. Above that, a green and gray tunic belted loosely at the figure’s waist, a long scarf, and a face hidden beneath the wide brim of a pointed hat with two feathers sticking out of it. Banjou’s first impulse was to put the tree at his back and bring his fists up to his face, but whoever had come through the woods didn’t seem concerned with anything but the rabbit, which spun just as the figure scooped it up. Now that they weren’t slouched over anymore, Banjou could see the face of the person clearly. A round face, with dark hair and dark eyes that almost matched the rabbits for their intensity and surprise. This attention was completely directed at the little animal, rather than the human being just a few paces away. 

Banjou could have run, he knew that, but he didn’t. The rabbit kicked a little, squirming despite the relatively solid hold it was in. Contemplation over, it was far more eager to run. It took a moment for the man holding the rabbit to realize the direction of the creature’s distress and look up, meeting Banjou’s gaze directly. 

“Oh?” A long pause, followed by a nod of realization. “A hunter?” He lifted the rabbit so that its dangling hind legs swayed back and forth, “Sorry, he wouldn’t make a very good meal.” 

The rabbit, punctuating the statement, kicked indignantly. 

For Banjou it was as though the echo of the words he had thrown to the woods had come back after a long delay, a what-the-hell extended long past its intended lifespan. There was a lot Banjou didn’t know, sure, but he knew he didn’t look like a hunter, barefoot and unarmed in his gallows rags. And what the hell was he supposed to do, disagree? He could take this scrawny little whatever in his big hat, even out of practice. He could do it even though his legs were begging him to do something, anything other than move from that spot unless it was sitting for a very long time. His fists could take it, as scratched from the wood's reaction his hurried escape as they were. How much lower was it possible to sink, anyway? He could wring a few pieces of gold off this guy and maybe make it a few towns over to an inn that didn’t care so much if your face resembled the one on the wanted poster hanging outside. Banjou shifted his weight, feeling his muscles settle back into a familiar fighting stance despite their complaints. 

Suddenly a distinctive sound rang out through the trees. Horses hooves, crushing twigs and leaves, the scraping of armor brushing against the bark. The rabbit and its friend seemed to have noticed, too, but Banjou didn’t have time to mull over the two of them. Or mug them, for that matter. He took off into the woods despite the better counsel of his body. It took perhaps longer than it should have for Banjou to notice the man and the rabbit were running, too. They were almost keeping pace with him, which was frustrating. What the hell could put an odd couple like that on the run from the authorities?

The sound faded, but the memory of it remained loud, clanging about in Banjou’s head in tune with the pounding of his heart. He slowed reluctantly, fighting off the exhaustion with the promise of just one more step, then another, until he couldn’t keep it any longer. He stopped, breathing hard, hands braced on his knees. The rabbit and its friend stopped running, too, coming to a more leisurely stop. Two sets of bright eyes scanned the trees again, considered the circumstances, and settled on Banjou once more. 

“Ahh,” It was astounding that the big hat didn’t fall off as the man spoke, tilting his head back in the direction they had run from, “The imperial guard, huh? What did you do?”

“Nothing! I didn’t kill anyone!” Banjou turned to fix a glare at both of the accompanying parties and found that neither of them had been looking in his direction at all. 

The man’s mouth drew itself into a slow “o.” He lifted the rabbit so it could perch on his shoulder, then unslung a wooden staff from a loop on his belt. “I knew you looked familiar, Mr. Murderer.” 

“I didn’t kill anyone!” Banjou was shouting now, couldn’t help the repetition of the phrase that had framed his past year. He was standing despite the way even that small exertion made him shake. He brought his fists back up with him. 

A twirl of the staff that left the trinkets tied to its curved tip spinning. “Very believable, Mr.  _ Accused _ Murderer. I’ll be apprehending you, then.” 

Banjou found himself crashing back down with only a slight swing of the staff as an indication of what had happened. He got back up again, eyes trained on the wood rather than the wielder. “If you thought those guys were after you, why the hell are you sticking around?”

“Why don’t you just head back to jail and save me the trouble?” 

This time when the staff spun, Banjou caught it with one hand. “I’m not going back there just die like the freak of nature they think I am!” Smoke came in curls from the wood where his fingertips touched it. “And so what if I am? I still wouldn’t kill anyone!”

The man’s eyes darted back and forth, as if in assessment. “Freak of nature?”

“You don’t believe that either, huh?” The wood crackled, snapped, burned. 

Neither of them saw the horse until it was almost on top of them. Banjou let go of the staff and stumbled backward, while the man with the rabbit adjusted the brim of his hat so it obscured his face to the horse’s rider. Banjou could still see him, even though he wasn’t able to decode the expression playing out in his eyes. 

Whoever it was on horseback didn’t feel like getting down, but something about the voice seemed familiar. “You’re that spellcaster. From the Mephistopheles’ Market.” 

Silence from beneath the brim of the hat. 

“I would appreciate your assistance in returning that criminal to his place at the gallows.” 

Banjou took a step backward. This was it, then. After all that, he was still gonna die. Slightly delayed, but still happening. He braced himself against a tree, reeling from all of it. Once more, with feeling: “What the hell?” He shook his head, “I was a bullshit knight, yeah, but I still wouldn’t... I didn’t kill anyone...” 

Banjou felt a tug at the leg of his burlap pants. He looked down to find the black and white rabbit and wondered if he was just projecting urgency onto its fuzzy face. He looked up and found human eyes with the same expression. 

“Go,” the man mouthed, then whispered, “Go!” 

The rabbit had stopped tugging and hopped into the underbrush to Banjou’s left. It fixed him with one last stare and scampered off. 

So, like the what-the-hell kind of day it was, Banjou followed. 

The rabbit was easy to track in the shades of green and brown that abounded as it bounded through them. Somehow the task of following the little creature distracted from the pain of running, and maybe more than that, because Banjou didn’t notice immediately when the wide-brimmed hat appeared again just ahead of him. Now he had both to keep track of, weaving between the trees with the certainty that he could keep up, that he had to. What had happened to the horse and rider and all who accompanied the still familiar but unplaceable pair was technically his problem, but Banjou couldn’t figure out why he was now sharing that problem with this person he’d just met. His fatigue-addled brain figured that it wasn’t worth spending any energy on for the moment, though. 

Banjou couldn’t tell how much time had passed before the two in front of him slowed. He followed suit, keeping his distance just a ways back. The trees broke formation just ahead, and he could hear human voices and... music? Banjou pushed past man and rabbit for a better look. Just one building stood in the foreground, a tavern sign dangling from a post above the door. There were a barn and stable adjacent to the tavern, and beyond that the edges of a village, cobblestones leaking into the clearing that the tavern occupied. He couldn’t look for too long, though, a hand grabbed him by the collar of his shirt and dragged him back into the cover of the trees. 

The rabbit had resumed its perch on the man’s shoulder. “Your face is all over town, you know. We’re going there.” He pointed to the barn and stable next to the tavern. 

Banjou didn’t know how he could have forgotten the hanging announcements, with the way the guard that had dragged him to the gallows had grinned over his likeness on the parchment. It pissed him off just to remember. Still, he didn’t wander back out, even if he couldn’t tell what they were waiting for. 

“Hey,” Banjou spoke without looking at his company, “Why’d you save me, anyway?”

“I believed you. That’s all.” Even said, the rabbit looked skeptical. 

Banjou had been about to offer his thanks when something was smacked down on his head. A few seconds of confusion discerned that it was the pointy hat he’d been following all this time. 

“Like this,” the man who had been wearing it motioned pulling down the sides. Banjou did as directed and received a nod of approval accompanied by what could almost be a smile. “This way.” 

Again Banjou found himself following the two of them, but at a walking pace across the clearing and then into the barn, up a ladder into the hayloft. The ceiling was low enough that both of them had to bend over slightly to stand in it. The smell of horses was thick in the air, despite the fact that Banjou hadn’t seen any in the stables. It was a great improvement from prison, nonetheless. 

“Stay here until I get you. That’s not too hard to remember, is it?” The man held out one hand in expectation of... something. His hat?

Banjou had to bend over even farther to get the thing off his head but managed to hand it to its rightful owner without tearing it. “I’m not an idiot.”

“Mmhm,” The man dusted off his hat and made his way to the ladder, waiting until he was one step down to replace it on his head, “Don’t set anything on fire, either.” 

“Alright, alright,” Banjou sat in the hay and look one long, slow, breath. He lay back with every intention of trying to work out what the day had been, what the hell he was going to do next. If he could clear his name, maybe...

Banjou was asleep before he realized he’d never asked for the man’s name. 


	2. ab homine quaesivi quis esset

 

_ There was only the rain and the way it slapped against the roof of the barn, like a hail of arrows.  _

_ The hay smelled of wetness, and his head felt full of the same stuff, mushy and insubstantial. Something warm on his lap, though, the sound of a door creaking open. He knew those things but lacked any recollection of why he knew them, of how he came by that knowledge. His head was far emptier than the barn. The thing on his lap was tangible, though. A black and white rabbit, serenely curled up across his knees, with ears that twitched as it breathed. He couldn’t truthfully state any recollection of rabbits, either. He stared at the lump of fur as it moved up and down as if prolonged examination would yield some answers. Somehow, that didn’t seem the correct methodology for this particular problem. But there was another question, a larger one, that loomed over him with far more importance than the rabbit.  _

_ He looked up to find that a person was looming over him, too. A middle-aged man with wooden-framed spectacles and dark, oiled back hair. There was a leather apron tied around his waist, but not of the smithing or butchering variety. Somehow he felt as though nailing down this stranger’s identity might be the first step in figuring out his own, which he seemed to have misplaced among the hay that still occupied his mind. Looking up made his head hurt, but maybe this stranger would have some more clues for him. The ones in his lap were proving entirely insufficient.  _

_ “Where... is this?” Words tasted so strange on his tongue and he found the question without looking for it, “Who am I?” _

 

***

 

A year as an amnesiac. It was hard to measure a year like that, harder still to say if it was a well-lived one or not. Still, Sento Kiryuu was relatively sure of the grace with which he was managing it. He had a job (illegal, but ever-fascinating), a roof over his head (though it was only the roof the groom’s shed of a stable could offer, so it leaked) and a convicted murderer sleeping in the hayloft (Ryuuga Banjou, he’d gone back to check the posters. The illustration was sub-par, to say the least). And while certainly, the last thing on that list was of some concern, there was a feeling he couldn’t shake that had first made itself known at the words of the aforementioned convicted murderer.  _ Freak of nature. _

Sento was a spellcaster, so being a statistical and biological abnormality was well within his wheelhouse. People with his capabilities were few and far between, and even those that were certain to be out there most likely couldn’t claim the same prowess with the arcane that Sento had. The discovery of his brilliance in all matters of magic had been a comfort when he was still stumbling through those first few foggy-minded days. It was something he discovered in part through the help of the man who had found him in the barn and owned the tavern adjacent: Soichi Isurugi. He had put Sento in one of the empty rooms above the tavern that first night and let him wallow in morose confusion. In the company of his rabbit, of course. 

That had been the start of the feeling, the pull of what could have been his memories. Soichi had offered to take the rabbit off his hands, even offering to make a nice meal of it. Sento had held the rabbit more tightly, protectively. It was important. He couldn’t say why, but it was. Soichi had laughed, said Sento would have to settle for what they had downstairs, which wasn’t much of anything. The tavern didn’t get a lot of patrons under normal circumstances. So when the bells on the door rang and denoted that someone had made their way in it was a special occasion. Soichi had practically thrown himself down the stairs to see who it was, and Sento had followed him, curiosity insisting he did so. 

It was a courier boy, not a patron, who stood sweat-soaked and nervous in the tavern doorway. Soichi hadn’t missed a beat, nonetheless, in giving the boy a solid whack on the head. 

“Hey, I told you not to deliver to me here!” Soichi shook his head.

The courier boy seemed even sweatier than before, partially dazed from his mild head trauma. “Yes, sir, I’m sorry, sir, but it says here it’s a sensitive delivery so I didn’t feel right just leaving it, sir!”

Soichi sighed. “Alright, alright...” He held out a hand, “So, what have you got for me?”

Time slowed, just for that instant. The courier boy retrieved something from his satchel, but as he brought his hand up to transfer the item to Soichi, the little parcel slipped like a trout from between his fingers. It slid across the tavern floor, between Soichi’s legs. The twine around the parcel snagged on a nail in the floorboards and came unknotted so that the wrapping of the parcel followed suit until the object came to a stop, naked, at Sento’s feet. It was a pocket watch. Why, Sento couldn’t help but wonder, was a pocket watch such a sensitive delivery? Something in the hay piles of his brain said that these things did not usually go together. He leaned down to pick up the watch, only half aware that Soichi was shouting something as he did.

There was a burst of light and color, an eruption of symbols that radiated from the watch as soon as Sento’s fingertips brushed against it. He should have been terrified, the courier and Soichi certainly seemed to be. But something about the shapes and what could be letters was familiar as they hung in the air. Time had frozen completely, but instead of frigidity Sento felt warmth bloom in his chest. It was magic on the pocket watch, he recognized it with surprising certainty. What appeared before him was discernibly malignant, but he could rewrite it, domesticate it. Sento felt the symbols against the palms of his hands and twisted them, rewrote them until the light spiraled back into itself. The pocket watch glowed in the tavern light, silent for a moment, and then began to tick. 

Soichi took half a moment of slack-jawed amazement, ushered the courier boy out the tavern door with all the speed he could manage, and then continued to stare. Concern flashed with an urgency across his face. “How are you feeling? Any numbness? Missing body parts? Inexplicable urges to speak in riddles?”

Sento had frowned, slightly. “No?”

Soichi nodded. “Ah, good!” He blinked, then ran a hand through his hair, stopping halfway through the motion. “Really??”

Sento hadn’t understood Soichi’s incredulity at first. The curse-breaking had come so easily to him, even with no memory of why he was capable of such a thing. The fact that he’d bested the pocket watch was a surprise as well; fate would have it that the very item that alerted Sento to his talents was the one that had stolen away the life of Soichi’s last curse-breaker. The details of the incident remained unclear, but it didn’t seem to matter now that the position was ready to be filled again. Sento hadn’t hesitated to take Soichi up on the offer, the warmth of magic still bright in his ribcage, the satisfaction of solving such a puzzle tapping out the beats of his heart. There was something else that he’d felt the instant the curse had come undone, but trying to quantify it was like catching a cobweb in a windstorm. Still, It was a good deal for him beyond such abstract fulfillment, too. He got his own lodgings out of it as well as free meals at the tavern whenever there was extra to go around, which was usually. The pocket watch still occupied a place on the table where he did most of his work. Soichi sold most of the items in his deliveries but had insisted Sento keep it. 

“Not like I had a buyer for it anyway!” He had patted Sento on the shoulder, “Call it an advance payment for your services.”

Sento liked to look at the watch when one of his other jobs wasn’t coming along as easily, or just when he felt like reminiscing, searching through the piles of hay that still crowded the corners of his thoughts. It was quiet company, much like the rabbit, who was currently languidly stretched over an empty part of his desk. Both of them were quite suddenly startled to attention by the sound of something crashing in the barn next door. He exchanged a look with the rabbit. Neither of them had to think very hard over the likely cause of the sound, but the prospect of interacting with Banjou again gave Sento a moment of pause. The feeling was back, the same one that tugged at him every time he cracked the spell on an object or worked out one of his own. Every item was something that could stir up his memories, too. The possibility was always there, shimmering just out of reach. Banjou felt that way, carried the same familiarity. He was going to have to treat this in the same manner as his work. A puzzle to be solved. That was what had swayed him to begin with, more than the solidarity of their abnormality that had sparked across his staff, more than the words spoken between the trees. 

To treat this as a job, the first step would be to gather more information. Sento exchanged another look with the rabbit, who didn’t seem entirely keen on accompanying him for this particular interrogation. Fair enough, the few minutes Sento had spent with Banjou gave him the impression that the escaped felon would be loud company. The rabbit wasn’t big on that, he’d learned that in their year together. The rabbit had a good number of preferences. Sento had gone to a pet shop to ask about proper care, and even the shopkeeper had admitted that such animals were not so particular. It came with upsides, at least-- the rabbit had a way of pointing out solutions to problems in Sento’s work that he hadn’t even thought of. Nonetheless, it was alone, and cautiously, that Sento exited his workspace and made his way to the barn. 

He found the source of the crashing noise was exactly as he suspected. Ryuuga Banjou was half-sitting on the floor of the barn, hay adorning his head. The ladder from the hayloft, luckily unbroken, lay to one side of him. The man looked uninjured, too. That was, in all likelihood, a good thing. 

“What happened to staying here?” Sento leaned against one of the empty corral gates. They were all empty. 

Banjou spat hay out of his mouth. “I got hungry.” He gave Sento a look that was half a glare, half genuine observation. “No hat.”

_ Obviously not,  _ Sento thought,  _ because you gave it a criminal association. _ Out loud, he said “So you are an idiot.” 

Before Banjou had a chance to utter an indignant response, the barn door clattered open again and Soichi, brandishing a broom, charged through the hay. He skidded to a stop at the sight of Sento, then looked at Banjou, then back at Sento, and aimed the business end of the broom at Banjou. 

“Hey! Criminals are bad for business, you know!” Soichi waved the broom with menacing intent, as though he were going after some wayward raccoon rather than an actual human being. 

Banjou, for his part, certainly seemed as threatened as the hypothetical raccoon might be. He scuttled backward in the hay, throwing Sento a wide-eyed look. “Hey! Defend me or something!”

Soichi swung the broom around and jabbed it at Sento. “Sento! Are you letting criminals into my barn?”

Seeto didn’t find himself entirely phased by the broom, and it wasn’t as though a denial was entirely possible at this point. “Yeah, I am.” 

Soichi’s lowered the broom slightly, blinking in surprise. “Really?” 

Explaining his reasoning for helping Banjou was going to be too abstract. Sento had to think of something more concrete in a hurry. He nodded at Soichi, slowly. “I was thinking he could help with my end of the business.” He gave Soichi a meaningful look. 

It took a full moment, but then Soichi made an expression like the lantern in his brain had just been lit. He lowered the broom, leaning on it with one arm and bringing his free hand to his forehead. “That’s our Sento! Nobody’s going to miss an accused murderer, huh?” He smacked more than patted Sento on the shoulder, “I’ll leave you to it, then.” 

It wasn’t entirely a lie. In all likelihood, Sento would be a better curse-breaker with the entirety of his memories at his disposal. But he really didn’t have any intention of actually using Banjou as a tester to make sure his curse-breaking had been successful, even if that was the impression he’d given Soichi. Still, maybe experimenting wasn’t that bad of an idea. He was curious about the spontaneous flames that had come from Banjou’s hands when they had met. A fight or flight reflex, maybe?

Soichi was halfway out the door when Sento stopped him. “Oh, could you get him something to eat? He might get more annoying if we don’t feed him.” 

“Got it!” Soichi gave a half salute, “Oh, are you hungry too, Sento? There’s still some meat and potatoes left from yesterday, you know.”

Sento shook his head. “I’m fine. Wouldn’t say to a cup of tea, though.”

Soichi gave a quick affirmative and the barn doors swung closed with a creak behind him. Once more, it was only Banjou and Sento in the slightly musty barn. 

“Meat and potatoes?” Clearly, Banjou had heard that part of the conversation, at least, “Man, it’s been a while...” 

“No potatoes in jail?” 

“Hell no. Stale bread on a good day, maybe.” 

“Anyway,” Sento sat in the hay across from Banjou, “For now, start by telling me about yourself? From the beginning.”

**Notes for the Chapter:**

> yay, chapter 2! things are starting to get interesting...
> 
> sento is very fun to write. i really enjoyed working on this chapter!
> 
> as always, comments are very appreciated. i hope you enjoyed it!

**Author's Note:**

> (dragon knight joke before someone else can make it)
> 
> hey there! i loved build and everyone in it so i was very excited to write something to express my love and that ended up, with the help of a friend, turning into this?
> 
> i know it starts a little retelling-y, which is why i tagged it that way! this is mostly for set-up purposes, it's headed in a different direction. the characters tagged don't all make their debut immediately, but they'll be there!
> 
> i'm not sure how regularly this will update considering i am busy and there's another fic i really want to write... i'm also not totally sure how far i'm going to take this concept.
> 
> also i don't know anything about latin. just enjoying the aesthetic of these titles. 
> 
> anyway, i hope you enjoyed reading! comments are always appreciated


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